Ink jet printing systems are known in which a print head defines one or more rows of orifices which receive an electrically conductive recording fluid from a pressurized fluid supply manifold and eject the fluid in rows of parallel streams. Printers using such print heads accomplish graphic reproduction by selectively charging and deflecting the drops in each of the streams and depositing at least some of the drops on a print receiving medium, while others of the drops strike a drop catcher device.
One traditional method of refilling fluid into a continuous ink jet fluid system was to use a simple, collapsible, refill container. This method relies on the system vacuum to squeeze ink out of the container. However, when the system vacuum has squeezed all of the ink that it can out of the container, the container still has a significant volume of fluid remaining in the neck, due to the inability to completely collapse the bottle at that location. This poses several problems. First, disposing of bottles still containing some volume of ink creates environmental safety issues. Another problem is that any amount of unused ink obviously results in some unrecovered cost of the refill fluid.
In an attempt to solve these problems associated with fluid remaining in the neck of a bottle, it would seem logical to put a tube in the bottle, extending from the cap to the bottom of the bottle. In this way, theoretically, ink will drain to the bottom of the bottle, so the application of the vacuum source there should be able to remove more ink. Unfortunately, a new problem was encountered with this method. As the ink is removed from the container, a vacuum is created at the top of the bottle which opposes the vacuum trying to remove the ink. Therefore, when the two vacuum levels are equal, removal of ink will cease and, again, a significant amount of ink is left in the refill container.
Thus far, removal of ink from the refill container assumed the restriction of relying on the fluid system for the vacuum source supplied during normal continuous ink jet operation. One possible fluid refill method relieves this restriction in an attempt to remove as much ink as possible from the refill bottle. In this method, the top of a non-collapsible refill container is vented to atmosphere, with the tube still extending to the bottom of the bottle. While this method eliminates the vacuum lock problem, it still does not remove all of the ink from the container because now the position of the tube relative to the last remains of ink in the container becomes important. And the optimum position of the tube relative to the last remains of ink is not achievable without the undesirable effect of increasing the cost of the container.
It is seen then that there is a need for a refill system and method which eliminates the environmental, as well as the cost inefficiency, concerns of emptying fluid refill containers.